Thermoplastic material containing absorbent pad or other article

ABSTRACT

Materials have at least one layer comprising a mixture of thermoplastic and other fibers. This latter layer may be thermobonded together and then densified along at least a section of the eventual peripheral edge margin of an article to be formed from the material. Thermoplastic material-containing cover sheets may also be secured to the core and densified in this manner. The entire eventual peripheral edge margin of the article is typically densified. The material is cut within the densified region or slightly outside the densified region to provide a soft peripheral edge. Absorbent materials may be thermobonded within the layer and surrounded by a densified edge to fix them within the article. The composite materials are used in manufacturing infant car seat liners and other articles. In addition, sections of the material may be densified and provided with weakened areas, such as perforations, to enable users to selectively separate the articles along the perforations.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates to absorbent articles which containthermoplastic materials and more specifically to single or multiplelayer composite articles which include at least one layer formed from amixture of thermoplastic and other nonthermoplastic fibers, such as woodpulp fibers.

2. The Prior Art

Although articles and materials formed of a combination of thermoplasticand other fibers, such as wood pulp fibers, are known, these priorarticles and materials suffer from a number of disadvantages.

U.S. Pat. No. 4,458,042 of Espy discloses an absorbent materialcomprised of a consolidated blend consisting essentially of wood pulpfluff and wetting agent treated spurted polyolefin pulp. The polyolefinpulp is from about 3% to about 30% of the total weight of the blend.Representative polymers for the spurted polyolefin pulps includepolyethylene, polypropylene and copolymers of ethylene and propylene.Mixtures of two or more of these polymers are also described as asuitable polyolefin pulp. The polyolefin pulp and wood pulp are blended,formed into a fluff pad and then consolidated by heating to atemperature above the melting point of the polyolefin pulp. Calenders,infrared heaters and pull-through dryers are described as representativeheating devices.

Although useful, absorbent materials formed in this manner tend to losefibers from their outer edges, particularly when shaken. In addition,pads of these consolidated materials have a relatively low Z directiontensile strength which makes them relatively easy to pull apart,especially at the peripheral edges. Also, pads of these materials do notimpede the leakage of liquid deposited on these materials from theirouter edges.

U.S. Pat. No. 4,609,580 of Rockett et al. discloses an absorbent floormat comprising a combination of a nonwoven liquid permeable wearsurface, an absorbent inner layer of a mixture of polymeric microfibersand wood pulp, and a liquid impervious film backing layer. Intermittentbonds within the periphery or field of the floor mat are provided. Thesebonds are formed by a patterned application of sonic energy or heat andpressure.

In Rockett et al., a nonwoven web of nylon, such as sold under thetrademark Cerex® from James River Corporation is listed as one exampleof a liquid permeable layer. The absorbent microfiber layer is describedby Rockett et al. as being an essential feature of this mat. This layeris described preferably as an admixture of thermoplastic microfibers and"other" fibers such as wood pulp or natural or synthetic staple fibers.The absorbent layer is stated to have a basis weight in the range offrom about 100-500 g/m² and preferably in the range of about 150-250g/m². The composition of this layer is described as ranging from about0-80% of the "other" fibers and preferably in the range of from about60-80% wood pulp fibers by weight. The microfibers are described aspreferably being of thermoplastic polymers such as polyolefins,polyesters or polyamides having a diameter on the average in the rangeof up to about 15 microns and preferably in the range of up to about 10microns. Polyethylene and polypropylene microfibers are identified asspecific examples.

The absorbent layer is described in this patent as preferably beingformed in accordance with the "coform" process described in U.S. Pat.No. 4,100,324 of Anderson et al. In the Anderson coform approach,streams of molten polymer are deposited in an airstream and combined bya secondary air stream containing, for example, wood pulp fibers. Acombination of the air streams causes the distribution of the wood pulpin the microfiber matrix. In addition, exemplary staple fibers, ifincluded in the "other" fibers, are listed as polyester, polyolefins,polyamides and mixtures thereof. Finally, the liquid impermeable surfaceis described as preferably being a film with examples beingthermoplastic polymers such as polyolefins, polyesters and the like,including polyethylene or polypropylene films. The film is described asbeing applied as a separate layer, coextruded, or coated onto theabsorbent web. Calendering the exposed absorbent surface or providing abottom adhesive layer are described as alternate ways of achievingliquid imperviousness of the underside of the floor mat.

The Rockett et al. floor mat has field bonds occupying up to about10-25% of the surface mat. If an opened, disconnected pattern of fieldbonds is used, Rockett et al. discloses that up to about 20 bonds persquare inch are provided. If a line pattern is used as described inRockett et al., the pattern is up to about 10 lines per inch on theaverage in any direction. In use, the floor mat may be positioned in aholder which surrounds the peripheral edge of the mat.

In forming an absorbent layer in the manner of U.S. Pat. No. 4,100,324of Anderson et al, the meltblown microfibers are softened, but are notabove their melting point when they are engaged by wood pulp or the"other" fibers. Consequently, the bonding that occurs between thesemicrofibers and the "other" fibers is relatively weak in comparison tothe bonding that results when a thermobonding approach is used.Thermobonding in this sense means raising the temperature of a mixtureof thermoplastic and other fibers to a temperature which is above a meltpoint of at least one of the thermoplastic fibers in the mixture. Whenthis happens, a much stronger fusing of the mixture results. Inaddition, by relying on field bonds to secure the floor mat together,the Z direction tensile strength of the Rockett et al. composite mat isrelatively weak. Moreover, the peripheral edges of the Rockett et al.floor mat are as weak as the interior areas of the mat and would notimpede the leakage of liquid from these edges.

Another example of a pad which exemplifies the prior art is described inU.S. Pat. No. 4,650,481 of O'Connor et al. The pad of O'Connor et al hasa liquid impermeable backing sheet, an overlaying liquid permeable facesheet and an absorbent coform layer between the backing and face sheets.The interior of the pad is provided with a quilted pattern ofcompression lines described as being formed by ultrasonic bonding, heatand compression or the use of glue and compression. In an illustratedexample, the pad is generally rectangular and the quilting lines appearto form a pattern of squares on the pad. The backing sheet is describedas being generally bonded to the absorbent material by adhesive.

The coform absorbent material of the O'Connor et al. patent is describedas being of meltable polymers and staple fibers formed as disclosed inU.S. Pat. No. 4,100,324 of Anderson et al. Typical polymers aredescribed as polyethylene, polyesters, nylon and other thermoplasticfibers. Staple fibers are described as including cotton, polyester,rayon, and nylon. A combination of polypropylene meltblown fibers andwood pulp fibers is described as preferred in any desired ratio, butpreferably with meltblown polypropylene fibers being present in anamount from between about 30% and about 40% by weight of the mixture.Examples of the backing sheet in O'Connor et al. include polymer films,such as copolymers of ethylene and vinyl acetate, nylon and polyesters.The preferred backing sheet films are identified in this patent as beingof polyethylene or polypropylene and a composite of polypropylene and alightweight spun bonded fabric. Spunbonded polypropylene is listed inthis patent as one example of a facing sheet.

During one method of manufacturing the O'Connor, et al. pad, the facingsheet is placed on a foraminous belt with meltblown polypropylene andwood fibers being deposited onto the facing sheet as it moves belowmeltblown producing nozzles. The coform thus becomes mechanicallyattached to the facing sheet. The combined coform and facing sheet isbrought in contact with an adhesively coated polymer backing sheet whichis secured to the coform side of the combination. The pad is thenembossed to form the quilting pattern.

The O'Connor et al patent suffers from many of the drawbacks of theRockett et al. floor mat discussed above. For example, coform providesrelatively weak bonding of a pad. In addition, there is a tendency ofthe pad of O'Connor et al. to leak at the edges. O'Connor, et al.recognizes this and describes an embodiment (FIGS. 6 and 7) directedtoward solving this problem. In this embodiment, the absorbent materialis centered but does not extend completely to the peripheral edge of thepad. Instead, the facing and backing sheets are directly connected atthe edge of the manufacture of articles, a need exists for improvedmaterials and articles of this type.

SUMMARY OF THE INVENTION

In accordance with one aspect of the present invention, a mixturecomprised of fibers of at least one thermoplastic material and otherfibers, such as wood pulp fibers, is thermobonded together by heatingthe mixture to a temperature above the melting point of the fibers of atleast one thermoplastic material in the mixture. The mixture may bedeposited on a traveling foraminous belt and passed through apull-through hot air thermobonder to supply the heat for thermobondingpurposes. The resulting web or sheet is used to form pads or otherarticles or the core for laminated articles. The thermobonded mixture iscompressed and densified along at least a section of the eventualperipheral edge margin of the article. Heat and pressure, such assupplied by embossing rolls, may be used to densify this edge section.This aspect of the invention also encompasses compressing andthermosetting or heat sealing the edges of the mixture of thermoplasticand other fibers regardless of how the remainder of the mixture isformed.

The article is then cut from the thermobonded web or sheet. The articlemay be severed from the web within the densified edge margin section, inwhich case the densified edge margin section extends to the peripheraledge of the article. Alternately, the article may be cut slightlyoutside of the densified edge margin section in an undensified area ofthe web or sheet. This produces a softer edge to the article while stillmaintaining the strength provided by the densified edge section. Thesofter edge may also be provided by perforating the outer edge of thearticle in the densified region. When the perforations are broken tosever the article, the resulting edge is relatively soft. The densifiededge section acts as a partial liquid barrier to substantially impedethe leakage of liquid across the edge section. The denser the edgesection, the greater the resistance to liquid flow. Also, a pattern ofdiscontinuous or interconnected spaced apart field bonds may be providedinteriorly of the periphery of the article for added strength.

As another aspect of the present invention, absorbent materials may beincluded in the mixture of thermoplastic and other fibers forming thearticle with the densified edge section. Following thermobonding, thesematerials tend to be locked within the pad or core to thereby minimizethe possible migration of these materials from the article. Thedensified edge section also helps to retain these materials from escapethrough the densified edge section of the article. As explained ingreater detail below, these materials may include moisture absorbentmaterials such as desiccants and super absorbents, oil absorbentmaterials, and odor absorbent materials. Suitable materials are of thetype which do not substantially degrade during thermobonding.

As described below in the detailed description, in accordance with theinvention a wide variety of thermoplastic and other fibers may beincluded in the mixture which forms the pad, or the core in the case ofcomposite or laminated articles. Without limiting the breadth of theinvention, these mixtures may include thermoplastic fibers and wood pulpfibers in varying percentages depending upon the desired application ofthe material. Also, natural and synthetic staple fibers, such as cottonand rayon fibers may be included in the mixture. In addition, more thanone type of thermoplastic fibers may be included in the mixture withsome fiber having a melting point higher than the melting point ofothers. During thermobonding, these latter thermoplastic fibers are notmelted, so that they retain their integrity and add to the strength ofthe resulting article. In addition, these latter fibers may be of arelatively long length in comparison to the other fibers for additionalstrength. Bicomponent thermoplastic fibers may also be included in themixture. In addition, to enhance the blending and degree ofthermobonding, wood pulp fibers may be included in the mixture which areon average generally either shorter than, or longer than, thethermoplastic fibers.

Also, the basis weight, taber stiffness, bulk and other characteristicsof the articles can readily be controlled. For example, the amount ofthe thermobonded mixture included within the article is easily varied toadjust the basis weight. In addition, the percentage of the surface areaof the field of the article which is bonded can also be varied. Inaccordance with the present invention, articles having extremely highbasis weights and loft can be produced. These articles exhibit a highdegree of tensile strength, including in the Z direction.

As a further aspect of the present invention, one or more cover layersmay be included with the core to provide a composite article. Thesecover layers may comprise thermoplastic sheet materials or webs whichare thermobonded to or otherwise secured to the core. In one illustratedembodiment which is particularly well suited for infant car seat liners,the core forming fibers are deposited on a nonwoven thermoplastic facingsheet as it travels along a foraminous belt or screen. melting pointthan the bonding temperature. A liquid impermeable backing sheet is thensecured to the surface of the core opposite the facing sheet to providea composite structure. Field bonds may be provided in the article eitherbefore or after the backing sheet is in place. The composite structureis compressed and heat sealed along the eventual peripheral edge marginof the infant seat liner and then cut as explained above. The backingsheet may be adhesively or otherwise secured at every point of contactto the core or may simply be secured at the field and peripheral bondareas. In addition, the backing sheet may be secured in place after thedensified edge margin is formed. In this latter case, the backing sheetis not densified at the edge margin but is otherwise secured in place,as by adhesive.

As another aspect of the present invention, the pad, with or withoutcover sheets, may be densified in a region, as by the application ofbeat and pressure, and then weakened in such region to define a tearline. Typically, the densified and weakened region extends within theinterior of an article to permit a user to selectively tear the articleas desired. More specifically, the weakened areas may comprise scorelines, but more preferably comprise perforations formed through thearticle. These perforated areas allow articles, such as infant seatliners, with optional openings to have such openings retained by theperforations closed when not needed.

As a still further aspect of the present invention, the field bonds maybe formed prior to, simultaneously with, or following the densificationof the edge margin of the articles. Although other approaches aresuitable, preferably one or more embossing rolls are used to form thefield and edge bonds. When a composite thermobonded core facing sheet isprovided with field and edge bonds, the embossing rolls are preferablyheld at a temperature below the melting point of the thermoplasticmaterials of the core so as to minimize any delamination of the core andfacing sheet. In addition, it has been found that a reduction inshrinkage results if the field bonds are provided prior to theperipheral edge margin bonds of an infant seat liner or other article.

Accordingly an object of the present invention is to provide improvedthermoplastic containing materials and articles from such materials.

Still another object of the present invention is to provide strongarticles formed of thermoplastic and other fibers and in particular toprovide such articles with edge sections of enhanced tear strength andwhich minimize leakage.

A further object of the present invention is to provide materials usablein efficiently manufacturing articles from thermoplastic and otherfibers, the articles being of either simple or complex shapes.

Another object of the present invention is to provide versatilematerials for articles of thermoplastic and other fibers, the articleshaving readily controlled and variable characteristics such as varyingbulks and basis weights.

Still another object of the present invention is to provide articlesformed of a mixture of thermoplastic and other fibers, the mixture alsoincluding optional absorbent materials such as super absorbents and oilabsorbents which minimize the risk of the escape or migration of suchoptional materials into the environment.

Still another object of the present invention is to provide articles ofthermoplastic materials which minimize the leakage of liquids and dustfrom the edges of such articles.

A further object of the present invention is to provide materials formedof thermoplastic and other fibers usable in making articles from suchmaterials at a cost effective and high volume rate.

Another object of the present invention is to provide textile-like highbulk materials formed of thermoplastic and other fibers.

These and other objects, features and advantages of the presentinvention will become apparent with reference to the following detaileddescription and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic side elevational view of one form of apparatus forcarrying out the present invention;

FIG. 2 is a schematic side elevational view of an alternate embodimentof a portion of the apparatus of FIG. 1;

FIG. 3 is a perspective view of a pair of embossing rolls utilized incompressing and heat sealing the peripheral edges of an article, in thiscase an infant seat liner, made in accordance with the presentinvention;

FIG. 4 is a schematic illustration of one form of apparatus used forproviding weakened areas, in this case perforations, in articles made inaccordance with the present invention and for cutting such articles fromthe material of the present invention;

FIG. 5 is a schematic illustration of an alternate embodiment of anapparatus for providing perforations in articles manufactured inaccordance with the present invention and for cutting such articles fromthe materials of the present invention;

FIG. 6 is a top fragmentary view of a portion of an article made inaccordance with the present invention;

FIGS. 7 through 9 are cross-sectional views illustrating a compositematerial in accordance with the present invention as it enters, as it iscompressed and bonded by, and as it exits from embossing rolls;

FIG. 10 is a cross-sectional view of a composite material in accordancewith the present invention following the formation of field andperipheral edge margin defining bonds;

FIG. 11 is a cross-sectional view of an article of the present inventionformed without cover sheets and showing the article cut in a densifiededge margin section thereof;

FIG. 12 is a cross-sectional view like that of FIG. 11 except that thearticle has been cut in an undensified area adjacent to the densifiededge margin section and outside the field of the article to provide asoft edge;

FIG. 13 is a perspective view of a mat in accordance with the presentinvention;

FIG. 14 is a perspective view of a towel in accordance with the presentinvention;

FIG. 15 is a front view of an infant seat liner in accordance with thepresent invention;

FIGS. 16 and 17 illustrate the infant seat liner of FIG. 15 positionedin two different styles of infant car seats;

FIG. 18 is a front view of one form of a changing pad in accordance withthe present invention;

FIG. 19 illustrates the pad of FIG. 18 after the pad has been folded;

FIG. 20 illustrates another form of changing pad in accordance with thepresent invention; and

FIG. 21 illustrates the pad of FIG. 20 after the pad has been folded.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS General Description ofMaterials Thermoplastic Fiber Containing Core

For purposes of convenience, the thermoplastic fiber containing layerwill be referred to herein as a core. However, it will be appreciatedthat in single layer articles or two layer laminated or compositearticles, the core itself respectively comprises the article eitheralone or with the other layer. Thus, in such cases the core would not besandwiched between two or more cover layers.

As previously mentioned, the core is formed from a mixture of at leastone thermoplastic material in fiber form in combination with one or moreother fibers. These other fibers may, and preferably do, include woodpulp fibers. While not structurally as strong, it is also within thescope of the present invention to include these added materials withincoform cores formed in the manner described in U.S. Pat. Nos. 4,650,481of O'Connor et al. and 4,609,580 of Rockett et al. and densified alongat least an edge section in accordance with the present invention tohelp retain these materials in place. The core forming fibers, on theaverage, have length to diameter or cross sectional dimension ratios ofgreater than 5 and typically have ratios close to 100 or more.

Suitable thermoplastic fibers are typically made from thermoplasticpolymers and are commercially available. These thermoplastic fibers havea high surface area to diameter ratio and are capable of melting whensubjected to heat. Representative thermoplastic fibers are made frompolyethylene, polypropylene, copolymers of ethylene and propylene, andcopolymers of propylene and other 1-olefins such as polyolefins pulpsmay also be used, in which maleic anhydride or styrene groups aregrafted. In some embodiments, the thermoplastic fibers are composedsolely of one type of thermoplastic. In other embodiments, they arecomposed of mixtures of two or more types of thermoplastic fibers.Bicomponent fibers, such as comprised of polyethylene and polypropylene,may also be used. Polyester fibers are still another example of suitablefibers. Cellulose acetate is a further example of a suitable fiber.

Suitable commercially available products for making the thermoplasticfibers include Pulpex® E-338 from Hercules, Inc., a polyethylene basedproduct; Kodel® from Eastman Kodak Corporation, a polyester basedproduct; and Vinyon® from Celanese Corporation.

As explained in greater detail below, assume the thermoplastic materialsare comprised of a mixture of more than one type of thermoplasticfibers, such as polyethylene and polyester fibers. In this case, duringthermobonding, the core is heated to a temperature sufficient to meltthe lower melting point thermoplastic fibers (polyethylene) withoutmelting the higher melting point thermoplastic fibers (polyester).Consequently, the integrity of these latter fibers is preserved andstrengthens the resulting core. In addition, by making the polyesterfibers of a relatively long length, such as equal to or greater thanabout one-half inch, cores of enhanced tensile strength are produced.Typically, in these mixtures the lower melting point thermoplasticmaterial is included in an amount of from about 5%-85% by weight, thehigher melting point thermoplastic material is included in a weightpercentage of about 1%-15% by weight, and other fibers, such as woodpulp, make up the remainder of the mixture.

As previously mentioned, the fibers mixed with the thermoplastic fibersto form the core may include wood pulp. Wood pulp fibers can be obtainedfrom well known chemical processes such as the kraft and sulfiteprocesses. In these processes, the best starting material is preparedfrom long fiber coniferous wood species, such as pine, douglas fir,spruce and hemlock. Wood pulp fibers can also be obtained frommechanical processes, such as ground wood, refiner mechanical,thermomechanical, chemimechanical, and chemithermomechanical pulpprocesses. Recycled or secondary wood pulp fibers and bleached andunbleached wood pulp fibers can be used. Details of the production ofwood pulp fibers are well known to those skilled in the art. Thesefibers are commercially available from a number of companies, includingWeyerhaeuser Company, the assignee of the present application.

In addition to wood pulp fibers, other nonthermoplastic synthetic andnatural staple fibers such as rayon, cotton and the like may be includedin the core forming mixture.

By making the other fibers of the mixture, such as the wood pulp fibers,either shorter on the average or longer on the average than thethermoplastic fibers, when blended the fibers of the mixture tend tobecome entangled to a greater extent. Therefore, upon thermobonding andmelting of the thermoplastic fibers, greater contact between thethermoplastic and other fibers is achieved and stronger bonds areproduced.

The optimal amount of thermoplastic and other fibers for a particularblend depends upon the bond strength and other properties desired in thefinal absorbent core. For cores intended to absorb aqueous basedsubstrances, thermoplastic fibers in an amount of from 5%-40% by weightand other fibers such as wood pulp in an amount of about 95%-60% byweight are suitable. In particular, blends of 80% wood pulp fibers and20% Pulpex® have proven to be preferred. In contrast, a greater oilabsorbency is achieved by increasing the thermoplastic fiber content ofthe mixture. For pads or cores in which this characteristic is desired,blends of thermoplastic fibers in an amount of approximately 95%-60% byweight and other fibers such as wood pulp in an amount of about 5%-40%by weight are desired.

Also, depending upon the particular application, other absorbentmaterials may be added to the mixture. After the mixture isthermobonded, these added materials are substantially retained in placedue to the thermobonding. The densified edge sections of the articlealso help retain these materials in place. Therefore, the tendency ofthese materials to escape or migrate from the article and into theexternal environment is reduced. Materials are selected which do notsubstantially degrade when subject to the temperature conditions thatare present during thermobonding. Also, by selecting thermoplasticmaterials with relatively low melting points, thermobonding can beaccomplished at temperatures which minimize the possible thermaldegradation of these materials. Among the suitable materials that may beincluded in the mixture are absorbent materials such as desiccants andsuper absorbent materials.

In practice, any absorbent or adsorptive material can be added to themixture. Representative examples include activated carbon, acid clay,active alumina, diatomaceous earth, silica gels and the like. Relativelynew developed superabsorbent polymers, such as cross-linked polyacrylatecommercially available under the brand name "Drytech" from Dow ChemicalCompany may also be included. Other absorbent substances generally usedin the form of a powder can conveniently be fixed in the core inaccordance with the process of the present invention.

In addition, oil absorbent materials such as polymers, includingpolynorbornene available under the brand name "Norsorex" from C.d.F.Chemie of France, may be included. In addition, deordorizing materialssuch as odor absorbing, odor masking, odor inhibiting and odoreliminating materials, may be included in the core forming mixture.Examples include baking soda, cedar oil and other fragrances. Again, thethermobonding of the core helps fix these materials in place.

Instead of including these absorbent materials in the core formingmixture prior to bonding, they may be placed on one or both surfaces ofthe core following the core formation. These materials may be includedin an adhesive coating on the core or simply sprayed on the core inliquid form and allowed to dry.

Finally, due to the methods of forming a core and articles of thepresent invention, cores of widely varying basis weights may bemanufactured.

Facing Layer Materials

In the case of an article formed of the core together with one or moreother layers, for convenience, one of these layers will be referred toas a facing or first covering layer.

The facing layer typically comprises a preformed sheet or web ofmaterial which travels toward a thermbonder. The facing sheet may be ofa nonwoven thermoplastic containing material. The core forming mixtureis deposited on the facing sheet to the desired depth. To preventmelting of the facing sheet during thermobonding, the facing sheet isselected to have a melting point which is higher than the melting pointof the thermoplastic fibers of the core which are to be melted duringthermobonding. When the facing sheet and deposited mixture pass throughthe thermobonder, the core fibers are thermobonded together and to thefacing sheet. Of course, the facing sheet can be secured to the corefollowing the formation of the core.

Thus, the selection of the facing sheet material will depend at least inpart upon the thermoplastic fibers included in the core. Representativefacing sheet materials include thermoplastic coated materials such asrayon which is resin or otherwise coated with a thermoplastic layer,polyolefin materials, spun laced polyester and polypropylene, resinbonded polyester and polypropylene, spun bonded polyester andpolypropylene, thermobonded polyester and polypropylene, cardedpolyester and polypropylene, melt blown polypropylene, polyethylenefilms of varying densities, polypropylene films, apertured films andother suitable materials apparent to those skilled in the arts.

In addition, if the illustrated manufacturing method is employed whereinheated air is pulled through the core and the facing sheet duringthermobonding, the facing sheet must be perforated or otherwisebreathable. Some commercially available suitable nonwoven continuousfilament products include Cerex® a nylon material from James RiverCorporation, Reemay®, a spun bonded polyester material from IntertecCorporation, and Sontara®, a spun laced polyester product from DuPontCorporation.

Again, a wide variety of facing sheet materials may be used. Thesefacing sheets are thermoplastic or thermoplastic containing for thoseapplications in which the facing sheet is to be thermobonded to thecore. If the facing sheets are secured to the core in another manner,such as by adhesive, then they need not be thermoplastic. Nonwovenmaterials are exemplary facing sheets because such materials readilyallow the passage of liquids to the absorbent core.

Backing Layer Materials

Again, for convenience, the layer of material on the opposite side ofthe core from the facing layer will be referred to as a backing orsecond cover sheet.

The backing sheet may be identical to the facing sheet and may besecured to the core during the thermobonding step. However, the backingsheet may also be comprised of a film having a melting point which isbelow the melting point of the thermoplastic fibers of the core whichare melted during heat fusing of the core. In such a case, thesematerials may be secured to the core following the thermobonding step.

Also, the backing sheet materials may comprise thermoplastic materialsso as to permit thermobonding or thermosetting of the backing sheetalong the eventual peripheral edge margin and at field bond areas of thearticle. Also, the backing sheet may comprise a liquid impermeablematerial which assists in containing liquids absorbed by the core andthrough the facing sheet.

Suitable backing sheet materials include, in addition to those mentionedabove in connection with the facing sheets, films of polyethylene,polypropylene and polyester and blends of these materials, linear lowdensity polyethylene films, nylon, polyvinylchloride films and fireretardant films. An example of a commercially available suitable film isSaran® from Dow Chemical Corporation.

Thus, a wide variety of suitable materials may be used in themanufacture of thermoplastic containing articles in accordance with thepresent invention.

Manufacturing Method

In a typical approach, the thermoplastic and other fibers to be used informing the core are blended by any of the known blending methods.Optional absorbent additives may also be blended in at this time Suchmethods include the preparation of a pulp sheet by conventionalpaper-making procedures or by conventional dry blending methods. Theresulting sheet is then rolled up to form a roll of core forming fiberssuch as indicated at 10 in FIG. 1. A sheet 12 is fed from roll 10 to afluff preparation zone 14. At zone 14, the web 12 is formed into a fluffpad by conventional methods such as hammermilling or air forming.

In other suitable approaches, the thermoplastic core forming fibers maybe fluffed separately from the other fibers, deposited in a hopper 16,and distributed by an air stream into the fluff preparation zone. Inthis case, the wood pulp and other fibers are similarly fluffed anddeposited in a hopper 18 and distributed by an air stream within thefluff preparation zone for mixing with the thermoplastic fibers from thehopper 16. Absorbent material additives may also be added to hoppers 16or 18. Vacuum air laying techniques may also be employed. Similarly,pulp sheets can be passed through a hammermill with the thermoplasticfibers being added in a separate step. Thus, the specific manner offorming the mixture of thermoplastic and other fibers that eventuallybecome the core of the article is not critical.

The core forming fibers may be deposited directly on a foraminous screen20 with the thickness of the fibers being determined in a conventionalmanner utilizing a doctor roll. In this case, the screen 20 carries thecore forming fibers through a thermobonder 22 which heats the fibers toa temperature above the melting point of at least one thermoplasticfiber material in the core. For example, the melting point of some typesof polyethylene pulp is 122° to 134° C. while the melting point of sometypes of polypropylene fiber is 160° to 165° C. This heat fuses thecore. Although calenders, infrared heaters, and other heating devicesmay be employed to heat fuse the core, the illustrated thermobonder 22comprises a flow-through dryer. The exact heating conditions, which canbe readily ascertained by one skilled in the art, must be determined forthe specific fiber blend being used. The time that the core spendswithin the thermobonder 22 is also readily ascertainable by one skilledin the art. Generally this time ranges from about one hundredmilliseconds to one minute depending in part upon the temperature of thethermobonder and the line speed at which the screen is traveling.Thereafter, the core can then be densified at eventual edge marginsections of an article to be formed from the core and otherwiseprocessed as explained below in connection with composite or laminatedarticles.

In the illustrated embodiment, a thermoplastic containing face sheet,such as a breathable, nonwoven, liquid permeable facing sheet web 24from a roll 26, is positioned on screen 20 upstream from the fluffpreparation zone 14. As facing sheet 24 passes through the fluffpreparation zone, the core forming fibers are deposited on the facingsheet to the desired depth. The unfused core forming fibers, indicatedat 28 in FIG. 1, together with the facing sheet 24, are carried by thebelt 20 into the thermobonder 22.

Although not required, the thermobonder has three stages 30, 32 and 34.In each stage, heated air enters from a respective inlet 36, 38 and 40.The entering heated air passes successively through the core formingfibers 28, the facing sheet 24, the belt 20 and to a respective exitoutlet 42, 44 and 46. A pressure differential is maintained across thetraveling materials to draw the heated gas through these materials. Forexample, the inlets may be pressurized relative to the outlets or avacuum may be applied to the outlets. The melted thermoplastic materialfibers of the core 28 fuse or thermobond the core to itself and also tothe face sheet 24. The temperature is such that the face sheet 24 is notmelted by the thermobonder 22. Protection of the face sheet from meltingis enhanced by passing heated air through the core and then to thefacing sheet.

Typical line speeds for the screen 20 are from 100 to 250 feet perminute with 150 feet per minute being a normal operating speed. Thethermobonder 22 includes an optional convection oven or apron 50. Thisoven maintains the temperature of the bonded core and facing as thesematerials travel toward a feature forming zone 54.

In a first approach illustrated in FIG. 1, a backing sheet 56, which maybe of a thermoplastic containing liquid impermeable material, is fedfrom a roll 58 to the exposed surface 60 of the core.

At feature forming zone 54, the multilayered or composite web is bondedor densified along at least a section of the eventual peripheral edgemargin of an article to be formed. Typically, the entire eventualperipheral edge margin of the article is densified at this time. Inaddition, optional field bonds may also be formed within the eventualfield of the article intermediate the peripheral edge margin. A numberof suitable processes may be used to form these densified areas. Theseinclude ultrasonic bonding and adhesive bonding. However, the preferredapproach is to emboss these bond areas. To this end, opposed sets ofembossing rolls 70, 72 and 74, 76 are positioned as shown. Theillustrated roll 70 comprises a field bond feature forming roll having aprojecting pattern of field bond forming contacts 80 which press againstthe face sheet and other layers of the composite material. Roll 72comprises a smooth surfaced anvil roll which is positioned against thebacking sheet 56. Similarly, roll 74 comprises a peripheral edge marginfeature forming roll having contacts 82 arranged to define thosesections of the eventual peripheral edge margins of the article whichare to be densified. Normally, the entire eventual edge margin of thearticle is densified by feature forming roll 74. Roll 76 comprises asmooth anvil roll which backs up the feature forming roll.

A conventional temperature control 90, 92, 94 and 96 is provided foreach of the respective rolls 70, 72, 74 and 76 for independentlycontrolling the temperature of these rolls. If the same materials arebeing used for the backing and facing sheets, typically these rolls arekept at the same temperature. If the rolls are held at temperaturesbelow the melting point of the thermobonding temperature of the core,the rolls are typically at 12°-130° C., depending upon the materials. Incases where the backing sheet 56 has a relatively low melting point,rolls 72 and 76 may be kept somewhat cooler (i.e. at 80°-110° C.depending upon the material) than rolls 70 and 74 to act as a heat sinkto assist in cooling the backing sheet 56 below its melting point.

The temperature of the embossing rolls 70 through 76 is preferably heldcooler than the melting point temperatures of both the core 28 and theface sheet 24. By maintaining the core 28 above its thermobondingtemperature when it reaches the embossing rolls, the feature formingrolls bring the core below the thermobonding temperature to thermoset orheat seal and compress the peripheral edge margins and field bonds inthe pad or other article. Also, the core and face sheet do not tend todelaminate when embossed with these cooler embossing rolls. This helpsto control the shrinkage of the article during embossing.

The field bond contacts 80 and peripheral edge margin bond contacts 82may be placed on the same roll. When articles from some of the abovedescribed materials were made in this manner, greater shrinkage of thearticle resulted than when the field bonds were provided before the edgemargin bonds. The peripheral bonds can be provided ahead of the fieldbonds. However, the preferred results were obtained when tbe field bondsand peripheral edge margin bonds were provided at successive embossinglocations. When formed first, the field bonds reduced shrinkage andtended to keep the layers of the composite material from shifting andbunching or gathering at the peripheral edge margins of the article.

A feature roll 74 and anvil roll 76 for densifying the eventualperipheral edge margin of the infant seat liner of FIG. 15 is shown ingreater detail in FIG. 3.

The nip gap between the contacts 80 and 82 and the corresponding anvilrolls is typically from about two to twelve thousandths of an inch withfour to eight thousandths of an inch being preferred. Bond strengthsignificantly decreases with a gap distance above twelve thousandths ofan inch. In addition, the depth between the contact and relief portionsof the feature rolls 70, 74 is sufficient to accommodate thickmaterials. Typically one-quarter inch to one-half inch spacing isprovided between the contact and the relief portions of these rolls.Consequently, high loft, deep relief products can be produced using theFIG. 1 apparatus. Embossing pressures are variable, depending upon thedesired density of the bonded areas, with 1,000 psi to 5,000 psiembossing pressures being typical.

The field embossed patterns typically comprise spaced apart embossedareas such as dots or intersecting lines For higher bulk products, fewerfield embossed areas are provided. Typically, no more than about 2%-4%of the surface of the article is embossed with field patterns, However,for some applications, additional embossing may be provided.

The Z direction tensile strength of articles formed in this manner isenhanced by the embossed areas. In addition, by embossing all orsections of the eventual peripheral edge margins of the article, thetensile strength of the article in X, Y and Z directions issubstantially improved, especially at the edge. In addition, a densifiedperipheral edge margin impedes the leakage of liquid from the padthrough the edge.

Following embossing, the articles may be separated from the compositematerial. Although the articles can be separated in the manufacturingline following embossing, in the illustrated embodiment the articles areseparated from the composite materials at a cutting location separatefrom the line. Instead, a laser, die, waterknife or other cuttingmechanism 100 is used to separate the composite materials into pads 102which contain the articles defined by the peripheral edge marginsembossed thereon. The separated pads 102 are then stacked in a bin 104for subsequent transportation to a cutting zone where the finishedarticles are severed from the pads.

As shown in FIG. 3, optional pin register defining contacts may beincluded on feature roll 74. These contacts form corresponding bonds onthe individual pads 102. These latter bonds may be registered with pins110 of bin 104 so that the individual pads 102 are aligned in the bin.More than one of the aligned pads can then be cut at a time at thecutting location with the pads being held in position by pins insertedthrough the bonds defined by contacts 108. Other pad alignmentmechanisms can also be used. Also, individual pads may be cut ratherthan cutting the pads in stacks.

For articles with a backing sheet 56 of materials like those of facesheet 24, the backing sheet may be added to the composite materialupstream of the thermobonder 22. This is shown by the roll 58 and sheet56 depicted in dashed lines in FIG. 1. Also, the facing sheet 24 may beadded following the passage of the core through the thermobonder 22.This is shown by the sheet 24 and roll 26 illustrated in dashed lines inFIG. 1. In this case, the bond between the face sheet 24 and core is notas strong as when both the core and face sheet pass through thethermobonder. Adhesive binders may be used to strengthen the bondbetween the face sheet and core if this approach is used.

In addition, an adhesive applicator, shown in dashed lines at 114 inFIG. 1, may be used to apply an adhesive coating to the surface 60 ofthe core or directly to the backing sheet ahead of the application ofbacking sheet 56 to the core. This adhesive serves to secure the backingsheet to the core at every point of contact between the backing sheetand core. This increases the strength of the composite material over thecase where field and peripheral bonds are the only means of securing thebacking sheet in place.

A wide variety of adhesive binders can be used for this purpose. Forexample thermoplastic resin adhesives and aqueous latexes are suitable.These binders typically have an activation temperature in the range offrom 70° to 100° C. This activation temperature is low enough to insureactivation of the adhesive binder as the binder passes through theembossing rolls. Ethylene/vinyl/acetate copolymer is one form ofsuitable adhesive binder. In addition, pressure sensitive adhesives arealso suitable.

In the approach illustrated in FIG. 2, the embossed thermobonded facingsheet and core is passed through a cooling chamber 120. In chamber 120,cool air is passed from an inlet 122, around the thermobonded facingsheet and core and to an outlet 124. Thereafter, adhesive is applied byapplicator 114 to the surface 60 of the core. The backing sheet 56 fromroll 58 is then positioned on this adhesively coated surface. Theassembled composite material is then optionally pressed between a pairof rolls 126, 128 to ensure a secure bond between the backing sheet 56and core at every point of contact between these components. Thereafter,the individual sections 102 of the material are singulated as previouslydescribed. With this approach, backing sheets of extremely low meltingpoints may be mounted to the core without being melted by the core andwhile permitting high line operating speeds. In addition, glues oradhesives may be used that otherwise could be degraded by heat from thecore. The adhesively secured backing sheets not only strengthen thecomposite material when bonded at every point of contact as previouslymentioned, but also prevent propagation of tears in the backing sheet.

As another approach, the backing sheet 56 may be placed on the corebetween the set of field bonding rolls 70, 72 and the set of peripheraledge margin feature forming rolls 74, 76, as shown in dashed lines inFIG. 2. In this case, the sheet 56 from roll 58 is embossed at theeventual peripheral edge margin of the article but not at the field bondlocations. Again, adhesive may be applied, as indicated by theapplicator 114 shown in dashed lines, to the surface 60 of the coreupstream of the backing sheet or applied directly to the surface of thebacking sheet which is to be secured to the core.

Improved bonding is provided at the peripheral edge margin of thearticle when the backing sheet is passed through the rolls 74, 76 incomparison to applying the backing sheet to the core downstream fromthese rolls.

FIG. 7 depicts the composite core, facing and backing sheets as theyenter the space between the rolls 70 and 72. Eventually, as shown inFIG. 8, the composite material is fully compressed between the contactpoints 80 of the roll 70 and the corresponding surface of the anvil roll72. Thereafter, as shown in FIG. 9, the material passes from the fieldbond defining roll 70, 72 to the peripheral edge margin defining rolls74, 76. As a result of this field bonding, compressed or dimpled areas132 are provided in the face surface of the composite material. Inaddition, a slight recess 134 is typically also visible in the backingsheet due to the compression of the backing sheet during field bondformation and as a result of removal of contacts 80 from the facingsurface.

As can be seen in FIG. 10, following the densification of the eventualperipheral edge margin sections of the article, a densified area 136remains along the eventual edge margin. Also, a slight depression 135 ispresent in the backing sheet opposite the depression 136. The edgemargin depressions are typically one quarter to three eighths incheswide. However, interior areas of an article which are to be perforatedare typically provided with slightly wider densified areas, such asareas which are about three-fourths inches wide.

At the cutting zone, the desired articles are cut from the pad sections102 by a cutting mechanism such as a die, laser, or water knife or othercutting mechanism. Water knife cutting systems in accordance with thepresent invention are shown schematically in FIGS. 4 and 5. Devicesusing a water knife, sometimes called a fluid jet, for cuttingstrip-like material are known. U.S. Pat. No 4,620,466 of Jumel et al.describes one such device. Similarly, a water knife may be used inconjunction with a cutting system sold under the brand name GerberCutterby Gerber Garment Technology, Inc. of South Windsor, Conn. Withreference to FIG. 4, a water knife 140 is supported by a computercontrolled movable support, such as found in the GerberCutter apparatusor the cutting machine of the aforementioned Jumel et al. patent. One ormore pad sections 102 to be cut are positioned on a table 144. The tableis capable of moving the pads in a direction perpendicular to thedirection that the water knife is moved by support 142. This combinationof motions, as described in the Jumel et al. patent and in the analogousGerberCutter system, allows any arbitrary shaped article to be cut fromthe pad sections 102. As previously described, the pad section 102 maybe held in place by optional pins 110 (see FIG. 1). A water stream 146from water jet 140 severs the articles.

FIG. 6 shows a pad section 102 having an infant seat liner 148 of thetype shown in FIGS. 15-17 defined thereon. This particular infant seatliner, as well as other products, has a densified area 150 extendingwithin the interior of the article. This area 150 is typically formed byfeature roll 74 at the same time as the formation of the densifiedperipheral edge margin 136 of the article. To accommodate the shoulderstraps of various types of infant car seats, the pad section 102 isprovided with weakened areas that increase the manual frangibility ofthe article so as to permit selective user opening of the article. Theseareas can comprise score lines formed during die cutting of the article.However, in the illustrated embodiment, these weakened areas compriseperforations 152 formed in the article by water knife 140 as the articleis severed from the pad section 102.

The entire shoulder strap receiving area of the infant seat liner 148may be perforated, or a portion thereof, indicated at 154, may be cutentirely through the pad with the remainder being perforated as shown.By perforating the infant seat liner, the user can open the liner asrequired to provide access to either a first shoulder strap receivinglocation 160 or a second shoulder strap receiving location 162. Theunopened sections of the infant seat liner 148 help to maintain theintegrity of the liner. For infant car seats of the type shown in FIG.16, perforations are opened by a user to provide access to the shoulderstrap receiving locations 160. In contrast, to fit the infant car seatof FIG. 17, the perforations are opened to permit positioning of theshoulder straps of this infant seat at shoulder strap receivinglocations 162.

To provide these perforations, a perforated template, such as a wirescreen 170 in FIG. 4, may be positioned above the areas of the padsections 102 which are to be perforated. As water knife 146 passes overthe screen 170, the water knife is interrupted by wires of the screen toprovide the perforations. The perforations are typically provided in thedensified areas 150 of the pad section 102. This results in a productwith a very strong edge and which resists leakage and dusting from theedge.

The FIG. 5 form of water knife cutting mechanism is similar to the FIG.4 form. However, instead of utilizing a wire mesh 170 to form theperforations, the water jet stream 146 is deflected by air, to aposition shown in dashed lines at 146' to a drainage trough 172. Byrepetitively deflecting and allowing the water jet stream 146 to returnto its cutting position, the cutting operation is interrupted so thatperforations are formed at desired locations 150 of the pad sections102. Air for deflecting the water knife is provided by a source 174through a valve 176 and to an air nozzle 178. The valve 176 iscontrolled by a control circuit 180 to open and close the valve asrequired to make the perforations. Other mechanical water jet deflectingmechanisms may also be used, such as deflector plates which reciprocateor otherwise move onto the path of the water jet to interrupt the jetand form the perforations. In addition, two water knives may be mountedto support 142 for cutting articles which are symmetric about a centerline from the pad 102.

The outer edges of towels, infant seat liners and other articles mayalso be perforated in the densified regions. When severed from pads 102,fibers are pulled apart slightly along the perforations and provide asofter edge. In the case of towels or other articles, plural articlesmay be in a roll or on a sheet and separated by densified areascontaining the perforations. The soft edge is then formed when thearticles are separated, such as during manufacture or by a consumer orother user.

As shown in FIG. 11, the cutting mechanism may be adjusted to cut thepad 102 to provide a peripheral edge 182 within the densified peripheraledge margin 136 of the pad. Alternately, as shown in FIG. 12, thecutting mechanism may be adjusted to cut the peripheral edge margin ofthe article at 184, a location which is slightly outside of thedensified peripheral edge margin 136. For example, the peripheral edge184 may be approximately one eighth inch away from the densifiedperipheral edge margin and outside of the field of the article. In thiscase, the peripheral edge is located in a relatively undensified area ofthe article. As a result, the edge will have a softer feel in comparisonto the case wherein the cut is made at 182 in the densified edge margin.The cut location may be adjusted such that a soft edge is provided atselected locations along the article while a harder edge is provided atother locations. In this latter case, only selected portions of thearticle would have a soft edge. However, in each case, the densifiedperipheral edge margin strengthens the article and impedes leakage ofliquids through the densified edge margin to the periphery of thearticle.

FIGS. 13-21 illustrate examples of various articles manufactured fromthe materials of and in accordance with tee methods of the presentinvention. These articles are described below in connection with anumber of examples. In connection with these examples, the variouscharacteristics and properties of the thermobonded cores and of thecomposite articles referred to herein, and through out the detaileddescription, are measured by the methods listed in Table I. In thistable, ASTM refers to the American Society of Testing Materials andTappi refers to the Technical Association of Pulp and Paper Industry.

                  TABLE I                                                         ______________________________________                                        Property Measurements                                                         Characteristics Test Method   Units                                           ______________________________________                                        Basis Weight    Tappi T-410 OM                                                                              g/m.sup.2                                       Caliper or thickness                                                                          Tappi T-411 OS                                                                              mm                                              Density         Tappi T-410 OM                                                                              g/cm.sup.3                                      Bulk            Tappi T-426 WD                                                                              cc/g                                            Machine Direction                                                             Tensile Strength                                                                              Tappi T-494   Newtons                                         Cross Machine Direc-                                                          tion Tensile                                                                  Strength        Tappi T-494   Newtons                                         Z Direction Tensile                                                           Strength        Tappi T-506   KN/m.sup.2                                      Taber Stiffness Tappi T-489   g-cm                                            Liquid                                                                        Capacity        ASTM-D535     ml/g                                            Elmendorf Tear  Tappi T-414   Newtons                                         ______________________________________                                    

EXAMPLE 1

In this first example, a single layer article or pad was formed bythermbonding a uniformly mixed blend or mixture of thermoplastic andother fibers of the type having a high surface area to diameter ratio.More specifically, Pulpex® E-33S from Hercules Corporation in an amountof 20 percent by weight of the article was mixed with 80% by weight ofwood pulp fibers. The specific wood pulp fibers utilized in this examplewere NB-316 fibers available from Weyerhaeuser Corporation. This Pulpex®is comprised of fibers having a diameter of greater than approximately 9microns. Fibers of this type have a greater average surface area thantypically found in the case of microfibers used in coform processes.Consequently, stronger bonding results.

The mixture was deposited on the moving screen 20 (FIG. 1) and passedthrough the thermobonder 22, within which the thermoplastic fibers weremelted to fuse the core. The fused core was also passed through aperipheral edge margin defining feature roll which densified the entireeventual edge margin of the article. Some of these pads were then cutwithin the densified area with a water knife so that the densified edgemargin extended to the peripheral edge of the pad. These pads likewisecan be cut outside of the densified area to provide a soft edge aspreviously described. The density at the densified edge margin has beentested at 0.3 to 0.6 g/cm³ and typically can be from about 0.3 to 1.0g/cm³. The Z direction tensile strength of the pad is anticipated to bethe same as the Z direction tensile strength of a multilayered pad.Thus, the dry tensile strength has been tested at 58.1 KN/m² at thedensified edge margin while the wet tensile strength has been tested at25.7 KN/m² at this location for an article with an edge margin of adensity at 0.3 g/cm³. Higher tensile strengths are expected for caseswhere the density of the edge margin is higher.

EXAMPLE 2

This example is like Example 1 with the addition of field bond areaswithin the field of the article. These field bond areas are spaced apartand may comprise point bonds, quilted pattern bonds, or other bondconfigurations. Typically, the field bonds occupy two to four percent ofthe surface area of the article. Pads of this type with widely varyingbasis weights have been manufactured in accordance with the presentinvention. The basis weights of pads made in this manner has ranged fromeighty to seven hundred fifty g/m². In addition, by varying the quantityof the field bonds and the basis weight, pads of varying taber stiffnesscan be produced, such as ranging from ten to one hundred g-cm.

At the densified edge sections of the pad, the pad resists dusting orthe loss of fibers at the edge and also resists leakage of liquidthrough the edge. Also, a pad with a densified edge can be obtainedwhich has a good Z direction tensile strength, such as described inconnection with Example 1.

Two placemats constructed in this manner were held approximately one andone-half feet over a dark piece of cloth. These placemats were rotatedthrough three hundred sixty degrees as they were being shaken for oneminute. Both placemats were then cut around their edges to eliminate thedensified edge region and then shaken again in the same manner. Fiveindividuals visually inspected the dark cloth for lint and agreed thatthere was no visible lint on the cloth when the uncut mats were shaken.However, they all observed a considerable quantity of lint on the clothwhen the cut placemats were shaken.

EXAMPLE 3

Articles formed of thermoplastic and other fibers held together by latexbonds or coformed and provided with a thermobonded edge in accordancewith the present invention also would exhibit the desiredcharacteristics at the edge of the articles. However, in the case ofcoform, the Z direction tensile strength of such articles would beweaker in the body of the articles. Also, the densified edge would alsobe somewhat weaker unless the edge is thermobonded, such as when thecore is thermobonded or when the densified edge is formed.

EXAMPLE 4

In this example, the pads or articles were of a single layer comprisedof a mixture of a first thermoplastic fiber of a first length which wasgreater than or equal to about one-half inch and present in a weightpercent of from one to fifteen. In addition, a second thermoplasticfiber shorter than the first length was included within the mixturetogether with wood pulp fibers.

In the specific example, the first thermoplastic fibers were polyesterfibers of either about one-half inch or about one inch in length, thesecond thermoplastic fibers were Pulpex® fibers (polyethylene) of ashorter average length and the wood pulp fibers were kraft fibers.Comparisons were made between mixtures comprised of (a) zero percentpolyester fibers, twenty percent Pulpex® fibers, eighty percent kraftfibers; (b) five percent polyester fibers (the test being run forpolyester fibers of both one-half inch and one inch in average length),fifteen percent Pulpex® fibers and eighty percent wood pulp fibers; (c)ten percent polyester fibers (again of one-half inch and one inchaverage length), ten percent Pulpex® fibers and eighty percent kraftfibers; and (d) 13.64 percent polyester fibers (again both size fiberswere tested), 13.64 percent Pulpex® fibers and 72.72 percent kraftfibers. Both plain (unembossed) and embossed pads were tested.

Table II illustrates the physical properties of the pads using woodpulp, Pulpex® and polyester blends. As is apparent from these tables,the addition of the polyester fibers substantially increased the wettensile strength of the pads over the examples tested without thepolyester fibers.

                                      TABLE II                                    __________________________________________________________________________    PHYSICAL PROPERTIES OF PULP PADS USING PULP                                   PULPEX ® AND POLYESTER BLENDS                                                                    Wet     Basis                                          Kraft                                                                             Pulpex ®                                                                       Polyester                                                                          Fiber                                                                             Condition                                                                          Tensile Weight                                                                             Density                                   Fibers                                                                            Fibers                                                                             1/2" 1"  of Pad                                                                             Strength (N/m)                                                                        (gm/m.sup.2)                                                                       (kg/m3)                                   __________________________________________________________________________    80  10   10       plain                                                                              23.6    176.3                                                                              38.3                                      80  10   10       embossed                                                                           22.4    176.6                                                                              44.5                                      80  10        10  plain                                                                              20.1    179.6                                                                              39.3                                      80  10        10  embossed                                                                           19.6    182.9                                                                              44.6                                      80  20   0        plain                                                                              9.51    163.2                                                                              38.8                                      80  20   0        embossed                                                                           10.9    164.3                                                                              43.3                                      80  20        0   plain                                                       80  20        0   embossed                                                    80  15   5        plain                                                                              22.1    175.4                                                                              39.0                                      80  15   5        embossed                                                                           22.5    118.1                                                                              45.4                                      80  15        5   plain                                                                              22.4    178.2                                                                              40.4                                      80  15        5   embossed                                                                           23.1    173.6                                                                              46.3                                      72.72                                                                             13.64                                                                              13.64    plain                                                                              40.5    192.7                                                                              39.7                                      72.72                                                                             13.64                                                                              13.64    embossed                                                                           34.1    176.7                                                                              48.3                                      72.72                                                                             13.64     13.64                                                                             plain                                                                              26.8    181.5                                                                              48.4                                      72.72                                                                             13.64     13.64                                                                             embossed                                                                           24.9    184.4                                                                              48.4                                      __________________________________________________________________________

EXAMPLE 5

It has also been unexpectedly discovered that a combination ofbicomponent synthetic fiber (such as Chori NBFH, Chori NBFI and relatedproducts) with fluff pulp at densities of from 26.5 kg/m³ to 200 kg/m³have exceptional tensile strength when thermobonded. This strength isenhanced by densifying the peripheral edge of products made from thesematerials. These fibers also enhance hydrophilic and oleophilicproperties of the finished products, depending upon the fiber used. Thethermobonding is carried out at or above the melting point of the sheathpolymer component but below the melting point of the core polymercomponent. Because of the exceptional strength of the product, the useof these bicomponent fibers provides excellent cost and performancecharacteristics.

EXAMPLE 6

This example is like Examples 1 and 2. In this example, it is proposedto add an absorbent material to the core forming fibers. For example,desiccants, silicon gels, or super absorbents and other previouslymentioned absorbent materials may be blended with the thermoplastic andother fibers. Following thermobonding of these materials, the absorbentsare effectively retained within the pad so as to minimize their escapeto the external environment. In addition, oil absorbents, such aspolymers including polynorbornene may be added. In addition, odorabsorbents such as baking soda or deodorizers such as cedar oil may beadded to the core forming materials. Cover sheets, including thosecontaining thermoplastic materials thermobonded to the core, may also beused to enclose the cores formed in this manner. Alternately, thesematerials may be coated or applied as a layer on the core and held inplace by adhesive and a cover layer. However, it is preferred tothermobond these materials within the core as this more effectivelyfixes or captures them in place. Again, by surrounding the article inwhole or in part with a densified edge, added retention of thesematerials would be achieved.

EXAMPLE 7

In this example, the core is comprised of 20 percent Pulpex® and 80percent wood pulp fibers. In addition, a facing sheet of a nonwovenliquid permeable thermoplastic material, in this case polypropylene, wasused and a liquid impermeable backing sheet film, in this casepolyethylene film, was used.

During manufacture, the core was thermobonded to itself and also to theface sheet in the thermobonder 22 (FIG. 1) at a temperature of about140°-145° C. for about five seconds. The dwell time in the thermobonderis typically increased for increasing basis weight cores. In addition,the face sheet and core were thermoset together at field regions withinthe article and all three layers were thermoset at the eventualperipheral edge margin of the article by feature forming embossing rollsat about 120°-130° C. and anvil embossing rolls at about 80°-110° C. Thearticle was then cut in the densified areas to form an infant seat lineras shown in FIGS. 15-17. Articles were also cut slightly outside of thedensified eventual peripheral edge margin to provide a soft edge.

The basis weight of these articles varied from 80 to 450 g/m² with 150to 300 g/m² being a preferred basis weight for infant seat liners and200 to 250 g/m² being the ideal preferred range. The taber stiffness ofthe infant seat liners can be adjusted from 10 to 100 g-cm and ispreferably from 20 to 50 g-cm. When positioned in an infant car seat,tested infant seat liners with a taber stiffness of from 35 to 45 g-cmtend to remain in place, although tapes or other securing mechanisms maybe used to secure the liner to the infant car seat.

One specific infant seat liner constructed in this manner had a basisweight of 229.5 g/m² at its densified edge, a caliper of 0.763 mm at theedge and an edge density of 0.305 g/cm³. The tensile strength of thisinfant seat liner at the compressed edge area of the liner in the Zdirection was 58.1 KN/m² when dry and 25.7 KN/m² when wet. Ranges oftensile strength at the edge from 25 to 50 KN/m² and up when dry andfrom 20 KN/m² and up when wet are desired for this particularapplication. For reference purposes, this specific liner will bereferred to as test liner A.

The density at the compressed edge area of the infant seat linertypically can be varied from 0.3 to 1.0 g/cm³. In addition, althoughvariable, the field bonds occupied an area of from about 2 to 4 percentof the entire surface of the infant seat liner.

Infant seat liners having a basis weight in the range set forth aboveprovide good cushioning, excellent thermal insulation, good absorbencyand adequate flexibility. Thermal insulation Of an R value estimated atfrom 2 to 5 is achieved with this construction, with higher thermalinsulation values being provided by higher basis weight infant seatliners. The total pad bulk of infant seat liners of this constructioncan typically range from 10 to 30 g/cc. In addition, the absorbencycapacity of these liners has been tested at typically 10 to 16 ml/g ofmaterial. The pad wicking rate can vary from 5 to 25 ml/minute dependingupon the pad construction. In addition, the tested edge wicking inml/minute was virtually 0 in the densified edge areas of the infant seatliner for liners tested with edge densities of about 0.5 g/cm³.

The tear resistance of the pad (determined in accordance with TAPPIT-414) in the machine direction varied from about 1,000 mN when no gluewas used to secure the backing sheet and the backing sheet was thermosetin place to about 4,000 mN when glue was used and the backing sheet wasnot thermoset to the core. This tear resistance is largely a function ofthe thickness of the backing sheet and the temperatures to which thebacking sheet bas been subjected. The ratio of the wet tensile strengthto the dry tensile strength of the total pad (determined in accordancewith TAPPI T-494) can vary from about 0.5 to 1.0 with the sameapproximate ratio being present in both the machine and cross machinedirections.

In addition, the Z direction tensile strength of the pad without gluebeing used for securing the backing sheet in place, and excluding thedensified regions of the pad, can vary from about 1 to 5 KN/m².

Infant seat liners in accordance with this construction have been foldedand unfolded over 5,000 times without failing. In addition, a nonwovenface sheet may be printed or otherwise provided with a decorativedesign. Although infant seat liners of this construction are expected tobe disposable, it is anticipated that they will last from one to twomonths in normal use unless they become soiled. In addition, asillustrated by FIGS. 15-17, articles of very complex shapes can beproduced.

EXAMPLE 8

This example is like example 7 except that the backing sheet iscomprised of a fire resistant material secured to the core at everypoint of contact with the core, as by adhesive, after the core andfacing sheet have been field bonded. More specifically, GF19 fireretardant filled polyethylene film from Consolidated Thermoplastics wasused. This film has a fire resistance of less than 1, and close to 0,inches/minute when tested in accordance with the Federal Motor VehicleSafety Standard 302. The core was comprised of 80% wood pulp fibers and20% Pulpex® by weight. In addition, the facing sheet comprised a cardedthermobonded nonwoven polypropylene APN 185 available from James RiverCorporation. In this case, the core has a lower fire resistance than thebacking sheet in the absence of fire retardant being included within oron the surface of the core. In addition, the basis weight of the articleaffects the fire resistance. With the basis weight of greater than about200 to 250 g/m² together with the use of a fire retardant film, thecomposite infant seat liner of the present invention as been found toburn at less than 4 inches/minute when tested under Federal MotorVehicle Safety Standard 302.

EXAMPLE 9

This example is like example 8 except that the backing sheet is securedin place by intermediate field bonds either with or without theadhesive. The use of field bonds and peripheral bonds increased the Ztensile strength of the composite article. However, the difference isnot noticeable to any significant extent if adhesive is also used tosecure the backing sheet in place. It was noticed, however, the articlehad a slightly lower fire resistance when the GF19 film was field bondedin this manner in comparison to the case when the film is not fieldbonded.

EXAMPLE 10

In this example, a pad having a nonwoven back sheet and nonwoven facesheet (i.e. APN 185 nonwoven sheet material) is provided with a corehaving a basis weight of from 150 to 300 g/m². In addition, less than 20bonds/inch² of the point or dot type bonds were provided. The articlesof this example can have a bulk of from 10 to 30 cc/gram. The densifiededge margin of the articles typically can be about 0.3 to 1.0 g/cm³ asexplained above. The Z direction tensile strength of these articles wasabove 20 KN/m² when wet at the densified edge margins and was greaterthan 50 KN/m² when dry at the edge margins. Moreover, the Z directiontensile strength of the articles when dry, at other than the densifiededge margin, can be from 1 to 10 KN/m² depending upon the percentage ofthermoplastic material included in the core. In addition, the ratio ofwet to dry tensile strength of these articles was about 0.5 to 1.0.Also, the machine direction to cross machine direction dry strengthratio was less than about 2 to 1.

EXAMPLE 11

For comparison purposes, two pads were constructed under the sameconditions used to produce test liner A of Example 7. The firstcomparison pad comprised a nonwoven face and nonwoven backing sheet (APN185 nonwoven sheet material) with a core of 100 percent pulp fibers. Thebasis weight of the article was 253.2 g/m² at a densified edge of thearticle, the caliper of the article was 1.42 mm at the densified edge,and the density of the article at the edge was 179.5 Kg/m³. This articlehad a tensile strength in the Z direction at the compressed edge of0.399 KN/m² when dry and 1.23 KN,/m² when wet.

The second comparison pad was a five layer pad. In this case, from topto bottom, the pad included a top sheet of nonwoven material, a secondsheet comprised of 80 percent wood pulp fibers and 20 percent Pulpex®, athird sheet comprised of 100 percent pulp, a fourth sheet comprised of80 percent wood pulp fibers and 20 percent Pulpex® and a bottom sheetcomprised of a nonwoven material. The basis weight of this particularpad was 247.0 g./m² at the densified edge of the article, the caliper ofthe pad was 0.812 mm at the densified edge, and the density of the padat the edge was 0.305 g/cm³. The tensile strength of this pad at thecompressed edge in the Z direction was 11.4 KN/m² when dry and 8.53KN/m² when wet.

In each of these examples, the tensile strength of the article at thedensified edge section is much lower than the tensile strength of thetest liner A as set forth in Example 7 above.

EXAMPLE 12

This particular example relates to the towel 199 shown in FIG. 14 whichis generally of a rectangular shape. The peripheral edge of the towel isdensified at 200. The edge of the towel can be perforated so that whenseparated from another towel, if formed in a roll, a soft edge results.In addition, point field bonds 202 are provided throughout the field ofthe towel. These field bonds are about 2 inches apart. The overall sizeof the illustrated towel is 91/2 inches by 161/2 inches.

This towel has a core formed of 20 percent Pulpex® and 80 percent woodpulp fibers. In addition, a 0.7 ounce/yard nonwoven thermoplasticmaterial, in this case APN 185 carded thermobonded nonwovenpolypropylene was provided as the facing and backing sheets. The facingand backing sheets are thermobonded to the core and heat sealed orthermoset at the edges.

The basis weight of the towel is approximately 175 g/m², the density ofthe towel is approximately 0.05 g/cm³, the taber stiffness of the towelis about 5 to 6 (and more specifically 5.4) g-cm, the thickness of thetowel is about 4 mm, and the absorbency of the towel is about 10 to 15ml/g. In addition, after being thoroughly soaked and hand wrung out, thereabsorbency of the pad, that is the ability of the towel to reabsorbmoisture, was about 5 ml/g.

The towel of this construction exhibited high strength, was wringablefor reabsorption purposes, and produced very little lint.

EXAMPLE 13

This example relates to the door mat 203 shown in FIG. 13. The mat ofthis example was constructed of a core comprised of 80 percent wood pulpfibers and 20 percent Pulpex®. Facing and backing sheets comprised of 1ounce/yard² APN 185 nonwoven thermoplastic material was used. The facingand backing sheets were thermobonded to the core and densified at theperiphery 204 of the mat.

The basis weight of this mat is variable, and is typically greater than500 g/m². A specific example of this mat had a core basis weight ofapproximately 700 g/m². The thickness of this mat was about 12.7 mm andthe density of this mat was approximately 0.05 g/cm³. The taberstiffness of this mat was approximately 250 g-cm, more specifically 254g-cm.

The field bond areas 206 of this example pad comprise a crosshatchedspaced apart diamond pattern formed of parallel bond lines extending ina first direction which are intersected by parallel bond lines extendingin a second direction. The parallel lines forming this pattern are aboutone inch apart. The overall dimensions of the illustrated mat 203 areabout 34 inches long and 24 inches wide. Although other field bondingpatterns may be used, field bond patterns which form compartments withinthe pad surface keep the core material of the mat from shifting in theunlikely event the core material separates from the cover sheets, suchas when soaked with oil or other liquid.

EXAMPLE 14

This last example relates to changing pads 211, 230 as shown in FIGS.18-21.

Changing pads of this construction include a liquid impermeablepolyethylene film backing sheet, a core formed of 80 percent wood pulpfibers and 20 percent Pulpex® E-338, and a nonwoven liquid permeablefacing sheet, such as used in Example 15.

Although variable, the basis weight of the changing pad is typicallyfrom about 100 to 200 g/m² and the density of the core of this pad isabout 0.05 g/cm³. Also, the taber stiffness of the changing pad is about25 g-cm although the taber stiffness varies with the bonding patternemployed in the pad.

In general, the illustrated changing pad is rectangular in shape. Thewidth of the pad is about 15 inches and the length of the pad is about23 inches. The densified periphery of the pad is about one-fourth of aninch wide. In addition, densified lines extend within the body of thepad so as to separate the pad into plural compartments. These lines areelongated, that is, much longer than they are wide. These compartmentsminimize the leakage of liquids from the pad. In addition, the densifiedperipheral edge also impedes the leakage of liquids from the edge of thepad. These interior densified areas also define fold lines, enabling thefolding of the pads into compact shapes. Typically, the fold lines areabout one-eighth inch wide, although they are not mandatory.

Referring to FIG. 18, the changing pad 211 of this construction has adensified periphery 210 and plural point bonds 212 within the field ofthe article.

A first fold line 214 extends longitudinally across the center of thepad 211 and separates the pad into side by side, in this case left-handand right-hand compartments. In addition, transverse fold defininglines, in this case at least two such lines 216, 218, extend across thechanging pad in a direction normal to the fold line 214. The fold lines216 and 218 subdivide the pad into an upper section 220, a middlesection 222, and a lower section 224. When the changing pad is foldedalong fold line 214 and then along the fold lines 216 and 218, acompact, folded changing pad results as is shown in FIG. 19.

The changing pad 230 of FIG. 20 is similar to the changing pad 211 ofFIG. 18. Therefore, like elements are given corresponding numbers andwill not be discussed in detail. In the embodiment of FIG. 20, insteadof a single longitudinally extending fold line 214, two parallel closelyspaced fold lines 232, 234 are positioned parallel to and spaced equaldistances from the longitudinal centerline of the pad. When the FIG. 20changing pad is folded along fold lines 216 and 21S and then along foldlines 232 and 234, a compact package is provided as shown in FIG. 21.

Therefore, in accordance with the present invention, a wide variety ofarticles of varying shapes and characteristics can readily be formedfrom thermoplastic and other fibers.

Having illustrated and described the principles of our invention withreference to a number of preferred embodiments, it should be apparent tothose of ordinary skill in the art that such embodiments may be modifiedin detail without departing from such principles. We claim as ourinvention all such modifications as come within the true spirit andscope of the following claims.

We claim:
 1. An absorbent article comprised of a thermobonded mixture offibrous material which includes thermoplastic fibers, the article havinga field and a densified peripheral edge margin of fiberous materialalong at least a section of the article, the densified peripheral edgemargin of fiberous material forming a substantial liquid barrier alongthe at least a section of the article.
 2. An article according to claim1 in which the densified edge margin extends to the edge of the article.3. An article according to claim 1 in which the densified edge margin isbounded at least in part by an edge of the article which is of a lowerdensity than the densified edge margin.
 4. An article according to claim3 in which the thermobonded mixture comprises a core, the articleincluding at least one cover sheet mounted to the core and densifiedalong at least a section of the article.
 5. An article according toclaim 2 in which the thermobonded mixture comprises a core, the articleincluding at least one cover sheet mounted to the core and densifiedalong the at least a section of the article.
 6. An article according toclaim 1 also having a pattern of densified areas in the field of thearticle.
 7. An article according to claim 6 in which the thermobondedmixture comprises a core, the article having a backing sheet of a liquidimpermeable material mounted to the core and a face sheet of a liquidpermeable material, the face sheet being mounted to core.
 8. An articleaccording to claim 7 in which the backing sheet is secured at everypoint of contact to the core.
 9. An article according to claim B inwhich the backing sheet is adhesively secured to the core.
 10. Anarticle according to claim 8 in which the face sheet contains athermoplastic material and is heat bonded to the core.
 11. An articleaccording to claim 10 in which the backing sheet is of a thermoplasticcontaining material and in which the face sheet, core and backing sheetare each densified and bonded together about the periphery of thearticle and at a pattern of bond areas within the field of the article.12. An article according to claim 9 in which the face sheet contains athermoplastic material and the backing sheet contains a thermoplasticmaterial and in which the face sheet, core and backing sheet are eachdensified and bonded together about the periphery of the article and ata pattern of bond areas within the field of the article.
 13. An articleaccording to claim 1 which is also bonded together at a spaced patternof bond areas.
 14. An article according to claim 7 formed in the shapeof an infant seat liner having a lower leg supporting portion, a centralseat supporting portion and upper body supporting portion.
 15. Anarticle according to claim 8 formed in the shape of an infant seat linerhaving a lower leg supporting portion, a central seat supporting portionand an upper body supporting portion.
 16. An article according to claim1 in which the thermobonded mixture comprises the core, the articlehaving a backing sheet mounted to one side of the core and a face sheetmounted to another side of the core.
 17. An absorbent article comprisedof a thermobonded mixture of fibrous material which includesthermoplastic fibers, the article having a field and a densifiedperipheral edge margin of fiberous material along at least a section ofthe article;the thermobonded mixture comprising a core, the articlehaving a backing sheet mounted to one side of the core and a face sheetmounted to another side of the core; and the article having a Zdirection tensile strength at the densified edge margin of fiberousmaterial of greater than 25 KN/m², but not greater than the breakingpoint of the materials, when dry.
 18. An article according to claim 17having a Z direction tensile strength at the densified edge margin ofthe article of greater than 50 KN/m², but not greater than the breakingpoint of the materials, when dry.
 19. An article according to claim 16having a basis weight of from 80 to 450 g/m².
 20. An absorbent articlecomprised of a thermobonded mixture of fibrous material which includesthermoplastic fibers, the article having a field and a densifiedperipheral edge margin of fiberous material along at least a section ofthe article;the thermobonded mixture comprising a core, the articlehaving a backing sheet mounted to one side of the core and a face sheetmounted to another side of the core; and in which the density of thearticle at the densified edge margin of fiberous material is from 0.3 to1.0 g/cm³.
 21. An article according to claim 1 having a taber stiffnessof from 10 to 100 g-cm.
 22. An article according to claim I having ataber stiffness of from 20 to 50 g-cm.
 23. An absorbent articlecomprised of a thermobonded mixture of fibrous material which includessome thermoplastic fibers, the article having a field and a densifiedperipheral edge margin of fiberous material along at least a section ofthe article;the thermobonded mixture comprising a core, the articlehaving a backing sheet mounted to one side of the core and a face sheetmounted to another side of the core; and the face sheet containing athermoplastic material and being heat bonded to the core, and in whichthere is a pattern of bonded areas in the field of the article, thearticle having a Z direction tensile strength at the densified edgemargin of fiberous material of greater than 25 KN/m², but not greaterthan the breaking point of the materials, when dry, a basis weight offrom 200 to 350 g/m², a density at the densified edge margin from 0.3 to1.0 g/cm³, and a taber stiffness of from 10 to 100 g-cm, the articlecomprising an infant seat liner having a lower leg supporting portion, acentral seat supporting portion and an upper body supporting portion.24. An article according to claim 23 in which the core contains asuperabsorbent material.
 25. An article according to claim 23 in whichthe Z tensile strength at the densified edge margin is greater than 50KN/m², but not greater than the breaking point of the materials, whendry and the taber stiffness is from 20 to 50 g-cm.
 26. An articleaccording to claim 23 in which the bonded areas in the field of thearticle occupy from at least about two to about four percent of thesurface area of the article.
 27. An article according to claim 23 inwhich there are less than ten bonded areas per square inch in the fieldof the article.
 28. An article according to claim 23 in which the coreis comprised of thermoplastic fibers in a weight percentage of from 5 to40 and in which the other fibers comprise wood pulp in a weightpercentage of from 95 to
 60. 29. An article according to claim 16 inwhich the core is comprised of thermoplastic fibers in a weightpercentage of from 5 to 40 and in which the other weight fibers comprisewood pulp in a weight percentage of from 95 to
 60. 30. An articleaccording to claim 1 in which the core is comprised of thermoplasticfibers in a weight percentage of from 5 to 40 and in which the otherfibers comprise wood pulp in a weight percentage of from 95 to
 60. 31.An article according to claim S in which the core is comprised ofthermoplastic fibers in a weight percentage of about 20 and in which theother fibers comprise wood pulp in a weight percentage of about
 80. 32.An article according to claim 1 in which the core is comprised ofthermoplastic fibers in a weight percentage of from 95 to 60 and inwhich the other fibers comprise wood pulp in a weight percentage of from5 to
 40. 33. An absorbent article having a core comprised of athermobonded mixture of fibrous material which includes thermoplasticfibers, the article having a field and a densified peripheral edgemargin of fiberous material along at least a section of the article;anda facing sheet and a backing sheet which each contain a thermoplasticmaterial, the facing and backing sheets being heat bonded to the core,and the core, facing and backing sheets being densified and bonded aboutthe periphery of the article and being densified and bonded at a patternof field bond locations within the field of the article.
 34. An articleaccording to claim 33 in which the facing and backing sheets are each ofa liquid permeable material.
 35. An article according to claim 34 inwhich the field bond locations comprise point bonds that are spacedapproximately two inches apart.
 36. An article according to claim 35comprising a towel having a basis weight of approximately 175 g/m², adensity of approximately 0.5 g/cm³, a taber stiffness of approximatelyfrom 5 to 6 g-cm, and an absorbency of approximately from 10-15 ml/g.37. An article according to claim 34 having a basis weight of greaterthan 500 g/m².
 38. An article according to claim 34 in which the articlecomprises a mat with a core having a basis weight approximately no lessthan 700 g/m².
 39. An article according to claim 38 in which the articlecomprises a mat having a taber stiffness of approximately 250 g-cm. 40.An article according to claim 38 in which the pattern of bond areascomprises a quilted pattern of intersecting parallel bond lines, theparallel lines being spaced approximately one inch apart.
 41. An articleaccording to claim 1 including a superabsorbent material.
 42. An articleaccording to claim 1 including a moisture absorbing material.
 43. Anarticle according to claim 1 including an oil absorbing particulatepolymer material.
 44. An absorbent article comprised of a thermobondedmixture of fibrous material which includes thermoplastic fibers, thearticle having a field and a densified peripheral edge margin offiberous material along at least a section of the article; and includinga deodorizing material.
 45. An absorbent article comprised of athermobonded mixture of fibrous material which includes thermoplasticfibers, the article having a field and a bonded densified periphery offibrous material and at least one elongated bond area separating thearticle into at least two compartments, whereby the elongated bond areaprovides a fold line about which the article may be folded.
 46. Anarticle according to claim 45 which is also bonded together at densifiedbond areas within the field of the article.
 47. An article according toclaim 46 in which the thermobonded mixture comprises a core, the articlehaving a backing sheet of a thermoplastic containing liquid impermeablematerial mounted to the core, and a face sheet of a thermoplasticcontaining liquid permeable material, the face sheet being bonded to thecore and being heat bonded and densified at the periphery of thearticle.
 48. An article according to claim 47 having a first set of atleast two spaced-apart transverse bond lines each extending across thearticle in a first direction and a second set of at least one bond lineextending across the article in a second direction normal to the firstdirection, the bond lines separating the article into pluralcompartments and defining fold lines for the article.
 49. An articleaccording to claim 48 in which the bond lines of the first set aregenerally equally spaced apart by a first distance and in which thereare at least two bond lines of the second set spaced apart a seconddistance which is substantially smaller than the first distance, wherebythe article may be folded about the bond lines of the first set and thenabout the at least two bond lines of the second set to provide a compactfolded article.
 50. A changing pad according to claim 49 in which thepad is of a generally rectangular shape and which the bond lines of thefirst set are parallel to one edge of the pad and the bond lines of thesecond set are normal to the one edge of the pad.
 51. An absorbentarticle comprised of a thermobonded mixture of fibrous material whichincludes thermoplastic fibers, the article having a field and a bondeddensified peripheral edge margin of fibrous material along at least asection of the article, the mixture of fibers comprising firstthermoplastic fibers of a first length greater than about one half-inchin a weight percentage of the core of from about 1 to 15, secondthermoplastic fibers of a second length shorter than the first length ina weight percentage of the core of from about 5 to 85, and wood pulpfibers in a weight percentage of the core of about 5 to
 95. 52. Anarticle according to claim 51 including a thermoplastic containingfacing sheet which is both thermobonded to the core and densified at theperiphery of the article.
 53. An article according to claim 52 includinga thermoplastic containing backing sheet bonded to the core.
 54. Anarticle according to claim 53 including a pattern of heat bond locationsin the field of the article.
 55. An absorbent article comprised of amixture of fibrous material which includes thermoplastic fibers havingat least one bonded densified region of fiberous material and a weakenedregion positioned in the densified region to define a tear line so as topermit selective severing of the portion of the article along the tearline and weakened region.
 56. An article according to claim 55 in whichthe weakened region comprises perforations positioned in the densifiedregion.
 57. An article according to claim 56 in which the densifiedregion is positioned along at least a portion of the periphery of thearticle so as to provide a soft edge along the periphery when severed.58. An article according to claim 57 in which the thermobonded mixturecomprises a core, the article having a backing sheet of a thermoplasticcontaining liquid impermeable material mounted to the core and a facesheet of a thermoplastic containing liquid permeable material, the facesheet being heat bonded to the core, the perforations extending throughthe face sheet, the core and the backing sheet.
 59. An article accordingto claim 58 in which the face sheet and backing sheet are also densifiedin the area of the perforations.
 60. An article according to claim 55bonded at its periphery by a bonded densified region and having at leastone bonded an densified area positioned at least partially in the fieldof the article, the weakened area being positioned in such latterdensified region to define a tear line so as to permit selectivesevering of the portion of the article along the tear line and weakenedarea.
 61. An article according to claim 60 in which the thermobondedmixture comprises a core, the article having a backing sheet of athermoplastic containing liquid impermeable material mounted to the coreand a face sheet of a thermoplastic containing liquid permeablematerial, the face sheet being heat bonded to the core, the weakenedareas comprising performations extending through the face sheet, thecore and the backing sheet.
 62. An article according to claim 61 inwhich the face sheet and backing sheet are also densified in the area ofthe perforations.
 63. A limited life absorbent article with a field orbody bounded by a peripheral edge, the article comprising a backingsheet of a thermoplastic containing material, a liquid permeable facesheet of thermoplastic containing material, an absorbent core locatedbetween the backing sheet and the face sheet, the absorbent corecomprising a thermobonded mixture of fibrous material which includesthermoplastic fibers, the core extending substantially to the peripheraledge of the article, the core, backing sheet and face sheet beingcompressed and bonded together at the peripheral edge of the article,and at least the core and face sheet being bonded together by a spacedpattern of bond areas in the field to the article.
 64. An articleaccording to claim 63 in which the core is comprised of thermoplasticfibers having a diameter of greater than approximately nine microns. 65.An article according to claim 64 in which the density of thethermobonded peripheral edge is from approximately 0.3 to 1.0 g/cm³ andthe edge has a tensile strength in the Z direction of greater than 20KN/m² , but not greater than the breaking point of the materials, whenwet.
 66. An article according to claim 64 in which the basis weight ofthe core is from approximately 150 to 300 g/m².
 67. An article accordingto claim 66 in which the spaced pattern of bonds is less thanapproximately twenty bonds per square inch, and in which the bulk of thearticle is from approximately 10 to 30 cc/gm.
 68. An article accordingto claim 63 in which the core is comprised of thermoplastic fibershaving a diameter of greater than approximately nine microns, in whichthe density of the thermobonded peripheral edge is approximately from0.3 to 1.0 g/cm³ and the edge has a Z direction dry tensile strength ofgreater than, but not greater than the breaking point of the materials,approximately 50 KN/m², in which the basis weight of the core isapproximately from 150 to 300 g/m², in which the spaced pattern of bondsis less than approximately twenty bonds per square inch, in which thebulk of the article is approximately from 10 to 30 cc/gm, the articlebeing formed from a generally planar web having a cross machinedirection and a machine direction, the dry tensile strength of thearticle in a direction perpendicular to a plane containing the articleand at locations other than the edge and bond areas is fromapproximately 1 to 10 KN/m², and the ratio of wet to dry tensilestrengths of the article in the machine and cross machine directions isfrom approximately 0.5 to 1.0.
 69. A limited life absorbent articlehaving a field and an edge, the article comprising:a uniformly mixedblend of wood pulp fibers and synthetic thermoplastic fibers; saidarticle having a pair of major opposed outer surfaces; said majoropposed outer surfaces of the article being compressed and heat sealedat spaced locations within the field of the article; and the entire edgeof said article being compressed and heat sealed.
 70. The article ofclaim 69 further comprising a cover enclosing said article to form apair of outer cover layers; andsaid core and at least one of said pairof cover layers being compressed and heat sealed together at said spacedlocations and along said edge.
 71. The article of claim 69 in which theblend also includes synthetic non-thermoplastic fibers.
 72. A limitedlife absorbent article comprising:a core comprising a uniformly mixedblend of wood pulp fibers and first and second synthetic thermoplasticfibers, the first and second synthetic thermoplastic fibers havingdifferent melting points; said second thermoplastic fiber having ahigher melting point than said first thermoplastic fiber; the core beinghead fused together at a temperature at least at the melting point ofthe first of the thermoplastic fibers and below the melting point of thesecond of the thermoplastic fibers so as to preserve the integrity ofthe second of the thermoplastic fibers; a cover comprising a first sheetand a second sheet enclosing said core to form a pair of outer coverlayers; said core and said first and second sheets being compressed andsealed together at spaced locations; the article having a Z directionwet strength of at least 20 KN/m², but not greater than the breakingpoint of the materials.
 73. An article according to claim 72 in whichthe blend also includes synthetic non-thermoplastic fibers.
 74. Anarticle according to claim 72 wherein said first synthetic thermoplasticfiber is a polyolefin.
 75. An article according to claim 74 wherein saidsecond synthetic thermoplastic fiber is a polyester.
 76. An articleaccording to claim 74 in which said synthetic thermoplastic fibers arebicomponent fibers.
 77. An article according to claim 74 in which saidthermoplastic fibers are shorter than said wood pulp fibers.
 78. Anarticle according to claim 74 in which said thermoplastic fibers arelonger than said wood pulp fibers.
 79. An article according to claim 74in which the second of said thermoplastic fibers are longer than saidwood pulp fibers.
 80. An article according to claim 79 in which thesecond thermoplastic fibers are generally at least one half-inch inlength and comprise from 1 to 15 percent by weight of the core, thefirst synthetic fibers comprising from 5 to 85 percent by weight of thecore.